This invention relates to systems and equipment used to workover or repair production oil well in a field environment. The new equipment is a structure with apparatus for positioning over a production oil well site for safe and efficient work and repair of downhole oil well equipment such as a sucker-rod string, well tubing and the like.
For production oil wells in production oil fields there is generally an artificial-lift pumping system using a surface power source to drive a downhole pump assembly. A beam and crank assembly creates reciprocating motion in a sucker-rod string that connects to the downhole pump assembly. The pump may contain a plunger and valve assembly to convert the reciprocating motion to vertical fluid movement. Wells may also be outfitted with a collection of valves and fittings that may be a production tree for extracting production fluids.
Workovers of production wells are often necessary in older wells to replace tubing and to remove material effecting the well production. Depending on the type of lift system and wellhead a lightweight workover unit specifically designed for running and retrieving rod strings and rod pumps may be used for well workovers. These rod units are generally truck-mounted for field use and configured to suit the relatively light work associated with rod-pumping servicing.
Lightweight workover units may currently be known, see FIG. 1, that have a structural support assembly 16, 18 attached or mounted to a flatbed truck or trailer at the rear portion of the truck bed 110. The structure is usually a rectangular tubular beam assembly positioned at the back edge of the truck bed that has support beams attached to be positioned and attach forwardly in the truck bed structure to support the positioning of a work platform structure over a wellhead site. The work platform floor may be slidably engaged by sleeve tubes or sleeved brackets 34 on vertically positioned rods 16 or tubes that are fixedly attached to the support assembly.
Current practice is to manually attach the work platform to the sleeve tubes with the work floor oriented horizontal to the work site ground. The work floor is then positioned vertically on the vertical rods or tubes using available external lifting equipment 116, winches, pulleys or block and tackle, derrick-mast-tower and draw works, or other power lifting apparatus to raise and lower the relatively heavy work platform to each position necessary for a work crew to work on the wellhead equipment as well as to move pumps and other well equipment to be repaired or replaced. At each position the work platform is pinned in place using position pins 36 inserted through holes in the sleeves and rods.
In addition, known workover units have a pneumatic, rotating arm unit 130 attached to a vertical beam 18 of the support assembly. The pneumatic arm, which has been used for many years on oil field workover equipment, is positioned in a retracted, general downward orientation above the inside edge of the attached work floor 32. The arm is for use in moving rods and pipes away from the wellhead when removed and to position rods over a rod string when being attached to the sucker-rod string. The pneumatic arm 130, 132, 138 swinging when activated can be dangerous to workers on the work platform, and the arm is not useful for positioning the work floor.
What is needed is a self-powered support assembly to more safely work with rods, pipes and other oil well equipment during workover; and to position the work floor at various positions and elevations to improve work efficiency.